More than a week after a gunman opened fire on a concert in Las Vegas, killing 58 people and leaving hundreds of others injured, authorities say those chaotic minutes are still coming into focus.

At a news conference Monday, Clark County Sheriff Joe Lombardo revised one of those key details: when, exactly, shooter Stephen Paddock injured Jesus Campos, the unarmed Mandalay Bay security guard who came to investigate his floor.

“What we have learned is Mr. Campos was encountered by the suspect prior to [Paddock’s] shooting to the outside world,” Lombardo said. He told reporters Monday that Paddock shot Campos at 9:59 p.m. local time on Oct. 1, roughly six minutes before turning his gun on the crowd at the Route 91 Harvest music festival.